U.S. patent number 6,195,529 [Application Number 09/041,007] was granted by the patent office on 2001-02-27 for transmission blocker for mobile radio stations and method for preventing transmission activities of a mobile radio station.
Invention is credited to Regina Baumle, Joachim Linz.
United States Patent |
6,195,529 |
Linz , et al. |
February 27, 2001 |
Transmission blocker for mobile radio stations and method for
preventing transmission activities of a mobile radio station
Abstract
The invention relates to a transmission blocker for mobile
telephones as well a method for preventing transmission activities
of mobile telephones in the vicinity of safety-relevant electronic
devices, comprising a device for transmitting radio signals as
interference signals in the frequency range of the relevant mobile
radio network in such fashion that synchronization of the mobile
telephone with a radio station and/or decoding of the information
in the signaling channel and/or recognition of the relevant signals
from the mobile radio network can be prevented.
Inventors: |
Linz; Joachim (D-53117 Bonn,
DE), Baumle; Regina (D-77756 Hausach, DE) |
Family
ID: |
21914212 |
Appl.
No.: |
09/041,007 |
Filed: |
March 12, 1998 |
Current U.S.
Class: |
455/1; 342/14;
455/103 |
Current CPC
Class: |
H04K
3/28 (20130101); H04K 3/41 (20130101); H04K
3/42 (20130101); H04K 3/43 (20130101); H04K
3/45 (20130101); H04K 3/84 (20130101); H04K
2203/16 (20130101); H04W 48/02 (20130101) |
Current International
Class: |
H04K
3/00 (20060101); H04K 003/00 () |
Field of
Search: |
;380/6,49,1,103,422,14,95 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 546 849 |
|
Jun 1993 |
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EP |
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0 568 824 |
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Nov 1993 |
|
EP |
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2 164 227A |
|
Mar 1986 |
|
GB |
|
Primary Examiner: Urban; Edward F.
Assistant Examiner: Jackson; Blane J.
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus, LLP
Claims
What is claimed is:
1. Transmission blocker to prevent transmitting activities of a
mobile radio station, especially a mobile telephone, in a mobile
radio system with a mobile radio network and with stationary base
radio stations, with the base radio stations transmitting signals
(S) as synchronization information for reception by the mobile
radio station in order to allow the mobile radio station to
transmit, including devices for generating and transmitting radio
signals as interference signals (SS) in the frequency range of the
relevant corresponding mobile radio network, in such fashion that
synchronization of the mobile radio station with a base radio
station by means of the signal (S) to be received by the mobile
radio station and emitted by the base radio station and/or a
decoding of the signal (S) transmitted by the base radio station
can be prevented by the mobile radio station and/or recognition of
the signal (S) emitted by the base radio station can be prevented
by the mobile radio station in a protected area (PA) that can be
established by the interference signal (SS) whose interference
signal power (PSS) and the transmission time of the interference
signal (SS) can be set,
whereby the device for generating and transmitting interference
signals (SS) comprises an interference spectrum generating unit
(SC), a radiating unit (AE), a control device (ST), and a power
supply (SV), and
a measuring unit (ME) is provided for measuring the power (PEN) to
be received by the mobile radio station, and the interference
signal power (PSS) of the interference signal (SS) can be
controlled by the measured values received.
2. Transmission blocker according to claim 1 characterized in that
the measuring unit consists of one or more receiving antennas (EA),
located inside or outside the protected area (PA), as well as a
measuring receiver (MF), and an evaluating and control device (AW)
that converts the information supplied by measuring receiver (MF)
into control instructions to control control device (ST), and which
is supplied by power supply (SV) of the transmission blocker.
3. Transmission blocker according to claim 2 characterized in that
a radiating device (AE) of the transmission blocker can be used as
a receiving antenna (EA).
4. Transmission blocker according to claim 1 characterized in that
the interference spectrum generating unit (SC) for generating
interference signal (SS) comprises a broadband pseudo interference
generator (RG), a frequency generator (FG) for generating a carrier
frequency, a mixer stage (M1) for transforming a base signal as the
interference signal into the desired frequency band, an amplifier
stage (VSI) for decoupling the interference signal, a bandpass
filter (BF1) for generating the desired frequency spectrum in the
frequency range to be interfered with (FB-STOP), another amplifier
stage (VS2) controlled by interference spectrum generating unit
(SC) for power amplification of the interference signal, and an
additional bandpass filter (BF2) for limiting the interference
signal outside the frequency range to be interfered with.
5. Transmission blocker according to claim 1 characterized in that
radiating device (AE) has a single antenna for creating a discrete
radiating point or a combination of spatially distributed antennas
(AE1 and AE2) or a slotted cable (AE3) or a combination of the
above devices.
6. Transmission blocker according to claim 1 characterized in that
the control device consists of elements for turning the
transmission blocker off and on and possibly includes power control
or regulation for the interference signal and/or a component
monitoring system and function display.
7. Transmission blocker according to claim 1 characterized in that
the power of interference signal (SS) of the transmission blocker
can be adjusted in form and strength in such fashion that no
disturbance is caused outside protected area (PA) and no negative
influence is exerted on safety-relevant devices located in the
protected area.
8. Transmission blocker according to claim 1 characterized in that,
in order to avoid influencing measuring unit (ME) by the power
radiated by the interference spectrum generating unit, the
evaluation and control device (AW) has a mode of operation such
that interference signal (SS) is switched off during the period of
time (T-MESS) that signal (S) is being measured, with period of
time (T-MESS) having to be chosen to be shorter than the
synchronization time of the mobile radio station.
Description
The invention relates to a method for preventing transmission
activities of a mobile radio station, especially a mobile telephone
in a mobile radio system with a mobile radio network and with fixed
base stations, with the base station transmitting signals into the
mobile radio network as synchronization information with a basic
power and the mobile radio station receiving the signals with a
receiving power that is reduced by the interference power present
in the mobile radio network, and the mobile radio station being
able to transmit only when it receives a signal with a receiving
power that exceeds a predetermined threshold value.
The invention also relates to a transmission blocker to prevent
transmission activities of a mobile radio station when working the
method.
Transmission blockers for mobile radio stations, such as mobile
telephones for example, to prevent transmission activities or to
block them have not been known previously.
In areas with safety-relevant electronic devices, a transmitting
mobile telephone can cause interference that can result in danger.
At the present time, attention is directed to such danger by spoken
or written warnings on the spot, given by stewardesses aboard
aircraft for example.
The holders or users of mobile telephones, such as cell phones,
usually cannot be recognized as such. The persons responsible for
safety, at airports, aboard aircraft, etc. for example, must
therefore depend on the potential users understanding these
warnings and behaving in a responsible way by switching off their
mobile telephones. This solution results in uncertain situations
and is therefore unsatisfactory.
The goal of the invention is to prevent mobile radio stations such
as mobile telephones that function according to known principles,
from transmitting in order thus to reduce the danger of
safety-relevant interference without the cooperation of the owner
or potential user, especially in protected areas PA limited in
space and time.
This goal is achieved by a method according to the invention
according to claim 1 as well as a device designed in accordance
with claim 1 and termed a transmission blocker.
Advantageous embodiments of the method and the transmission blocker
can be found in the characterizing features of the subclaims.
The method according to the invention for preventing transmissions
by mobile telephones with limitations in space and time or for
interrupting the transmission of mobile telephones is therefore
characterized by the fact that an interference signal with an
interference signal power is generated in the mobile radio network,
with the interference signal power being chosen to be large enough
that the signal that is radiated at the basic power by the base
radio station, upon receipt by the mobile radio station, no longer
exceeds the threshold value of the receiving power. In addition,
the invention proposes a device for working the method. The device
is termed a transmission blocker. The transmission blocker
according to the invention is characterized by the fact that it
comprises devices for generating and transmitting radio signals as
interference signals in the frequency range of the relevant
corresponding mobile radio network to prevent transmission
activities of a mobile radio station, especially a mobile
telephone, in a mobile radio station with a mobile radio network
and with fixed base radio stations, with the base radio stations
transmitting signals (S) as synchronization information for receipt
by the mobile radio station in order to permit the mobile radio
station to transmit, in such fashion that synchronization of the
mobile radio station with a base radio station by means of the
signal transmitted by the mobile radio station to be received by
the base radio station and/or a decoding of the signals transmitted
by the base radio station by the mobile radio station and/or a
recognition of the signals emitted by the base radio station by the
mobile radio station is preventable in a protected area defined by
the interference signals, their interference signal power, and the
transmission duration of the interference signals.
The method according to the invention and a transmission blocker
according to the invention that operates according to the method
have the following features:
1. The transmission blocker transmits radio signals as interference
signals that prevent the mobile telephone from synchronizing with
the so-called base radio station or Ifrom decoding the signals
emitted by a signaling channel of the base radio station as
synchronization information, or generally recognizing the relevant
signals from the mobile radio network.
2. The transmission blocker prevents transmission on all mobile
radio stations that can make transmission contact with the base
radio stations only when the relevant signals that serve as
synchronization information from the base radio station are
received and have been recognized perfectly by the mobile radio
station.
3. The transmission blocker uses an interference signal which,
owing to its nature and strength, has no negative influences on the
safety-relevant electronic devices present in the area to be
protected PA.
4. The transmission blocker can be adjusted so that it does not
have a disturbing effect on radio networks outside the protected
area PA within which it is employed.
5. Optionally, the transmission blocker can be provided with
equipment that limits its influence to the mobile radio systems
that supply the protected area in question, GSM or CDMA for
example.
6. Optionally, the transmission blocker can be provided with
equipment that enables it to measure the prevailing levels of the
existing mobile radio networks and to create an optimum
interference level by means of a corresponding interference signal
SS with an interference signal power PSS that is sufficient to
prevent the mobile radio stations, like the mobile telephones, from
transmitting.
The invention will now be described in conjunction with FIGS. 1 to
3, where
FIG. 1 shows the functional design of a transmission blocker;
FIG. 2 shows the functional design of a control device; and
FIG. 3 shows the functional diagram of the operation of the
transmission blocker in a mobile radio network, producing a
protected area.
A mobile radio system with a mobile radio network in which the
invention can be used, see FIG. 3, consists as a rule of several
radio stations, hereinafter called basic radio stations BS, that
radiate signals S with a basic power PB as synchronization
information. The power PB is damped by the radio field of the
mobile radio network, and signals S arrive with a very much reduced
receiving power PE at a mobile radio station MFS. Before this
mobile radio station MFS can transmit in order to get in contact
with the mobile radio network, it must first receive and decode the
synchronization information from a suitable base station BS in the
form of signals S. For this purpose, the receiving power PE of the
signals S transmitted by the base radio station BS and received by
mobile radio station MFS must exceed a threshold value of a
receiving power PE-MIN that can be determined in advance. This
threshold value or minimum value of receiving power PE-MIN is
determined accordingly from the specific minimum signal
interference interval for the individual mobile radio station as
well as the interference power PS present on the signaling channel
of the base function stations.
PE is always smaller than PB.
The same applies to a mobile radio station MFS already in the
transmitting state. In order to be able to maintain the link
between the mobile radio station and the mobile radio network, a
signal S that is regularly transmitted during the connection as
synchronization information from the base function on the signaling
channel must arrive at the mobile radio station with a power that
at least corresponds to the receiving power PE-MIN, in order to be
able to be received by the mobile radio station. Otherwise, the
link is eliminated (broken off) after a safety interval (typically
in the range of several seconds) specified as a rule by the mobile
radio station.
The method of the transmission blocker according to the invention
consists in increasing the interference power PS which is present
in every radio field, which leads to a reduction of the
transmission power B of signal S up to the receiving power PE
(PB-PS=PE) in a protected area PA to be protected by an additional
interference signal power PSS, so that in the protected area the
available transmitting power PB of the mobile radio network arrives
at the mobile radio stations located in the protected area PA with
a receiving power PE that has been reduced to the point where the
threshold value PE-MIN is no longer exceeded, in other words:
PB-PS-PSS is less than PE-MIN.
From this following blocking condition, the following methods for
blocking or preventing transmission activities of a mobile radio
station such as a mobile telephone:
A mobile radio station MFS which is switched on but not
transmitting will not perform any transmitting activities, or a
transmitting mobile radio station MFS will cease to transmit after
a short time, if the mobile radio station additionally receives an
interference signal SS on the channel or channels that a
non-transmitting mobile station uses in order to synchronize itself
with a mobile radio network or the channels that a transmitting
mobile radio station uses during a connection. Said interference
signal SS on a given channel at the location of the mobile radio
station has such a high interference signal power PSS that the
threshold value PE-MIN of signal S is not reached. The interference
signal SS comprises an artificially generated additional
interference power PSS which, in conjunction with the interference
power already generally available in the radio field, causes such
damping of the transmitting power PB on the way to the mobile radio
station that the threshold value PE-MIN of the receiving power for
the mobile radio station is no longer reached.
Protected area PA results from the area in which this blocking
condition is met. The goal of the transmission blocker is to
generate interference signals SS with a corresponding interference
signal power PSS and thereby to create protected area PA.
Transmission blocker SSP, see FIG. 1, generally consists of an
interference spectrum generating unit SE, a radiating unit AE, a
control device ST, a power supply SV, and optionally a measuring
unit ME.
There are various known methods of designing the interference
spectrum generating unit SE. The maximum output power of the SE is
typically in the range from -10 dBm to +20 dBm. The interference
signal shape generated by the SE must generally be chosen so that
the blocking conditions can be met in accordance with the
invention. However, in order to prevent influencing stations other
than the mobile radio stations, a signal shape is advantageously
used which has a uniformly distributed power in the frequency range
FB-S to be protected, but has as little power as possible outside
this area. In particular, pulsed power from time-multiplex systems,
known for example from the GSM system, is avoided. Instead it is
proposed that a broadband pseudo interference signal or a family of
discrete carrier signals or a corresponding frequency-modulated
signal be used as interference signal SS, with the family
corresponding to the channel pattern of the mobile radio
system.
The interference spectrum generating unit SE for interference
signal SS for example, as shown in FIG. 2, can consist of a
broadband pseudo interference generator RG, a frequency generator
FG for generating the carrier frequency, a mixing stage Ml for
transforming a basic signal to the desired frequency band of an
amplifier stage VSI for decoupling the interference signal, a
bandpass filter BF1 for generating the desired frequency spectrum
in the frequency range FB-STOP to be interfered with, another
amplifier stage VS2 controlled by the SE for power amplification,
and an additional bandpass filter BF2 for limiting the interference
signal outside the FB-STOP.
Radiating device AE can be an individual antenna for creating one
discrete radiating point or a combination of spatially distributed
antennas AE1 and AE2 or a slot cable, such as leak cable AE3 or a
combination of these devices. Since the radio field of both the
base function stations and the transmission blocker cannot be
delimited precisely there is a boundary area, at the edges of
protected area PA that can be varied in space and time, with an
undefined behavior of the mobile radio stations. The size of the
limiting area can be minimized by a suitable choice of radiation
device AE.
Control device ST in the simplest case can consist of elements for
switching the transmission blocker on and off or additionally of
power control or power regulation for interference signal SS and/or
a component monitoring device and function display for example.
Power supply SV provides the components of the transmission blocker
with current which it obtains from an existing onboard network for
example or from storage batteries in the case of small mobile
designs.
For acceptance reasons it may be desirable to minimize the power
and/or energy irradiated by the transmission blocker, down to a
value of zero in areas without any mobile radio supply.
To minimize the radiated power, the transmission blocker can
therefore be equipped optionally with a measuring device ME that
adapts the interference signal power of interference signal SS to
the signal to be interfered with in such fashion that only as much
power is radiated as is required to fulfill the blocking condition
reliably.
Measuring device ME regularly measures, on all channels of the
frequency range to be protected, the power that can be received by
mobile radio networks and accordingly controls the power of
interference signal SS by means of control device ST.
Measuring device ME consists for example of one or more receiving
antennas EA that can be located inside or outside protected area
PA, as well as a measurement receiver MF and an evaluation and
control device AW that converts the information supplied by
measuring receiver MF into control instructions for the control
device. ME is supplied by power supply SV of the transmission
blocker. Optionally, radiating device AE of the transmission
blocker can also be used as a receiving antenna EA.
In order to prevent measuring device ME from being influenced by
the power radiated by the transmission blocker, evaluation and
control device AW can switch of interference signal SS during
measurement time T-MESS of mobile radio signal S. T-MEISS must
therefore be selected to be shorter than the synchronization time
of the mobile radio station, such as a mobile telephone, which is
typically several seconds.
To minimize the radiated energy, the inertia of the mobile radio
stations during resychronization to a base radio station following
a synchronization loss can be utilized: optionally, the control
device can be supplemented by a time-dependent control in such
fashion that interference signal SS is generated only temporarily
so that the average energy radiated by the transmission blocker is
reduced.
To improve service in aircraft for example, the transmission
blocker can be deactivated apart from critical phases in an
aircraft during flight at high altitude for example, or during
prolonged waits on the ground. In this way, the passengers could be
permitted to use the telephone again during a prolonged wait on the
ground, since active mobile radio stations, such as mobile radio
telephones, can be deactivated if necessary within several seconds
by activating the transmission blocker, and this action can be
announced by service personnel making an announcement. For this
purpose, the transmission blocker can optionally contain operating
elements that allow control from both the aircraft cabin and the
cockpit for example.
The protected area PA generated by a transmission blocker does not
have to be continuous. Thus for example an extension of the
protected area of the aircraft cabin into the baggage compartment
by adding a radiating device AE connected by a cable with
interference spectrum generating unit SE can be advisable, see AE4
in FIG. 3, since mobile radio telephones that are not deactivated
there because of the lack of an ability to influence them during
flight could constitute a particular risk.
The spatial limitation of protected area PA is achieved by suitable
choice of the power of interference signal SS to be generated as
well as by a suitable choice of the location and nature of
radiating device AE. The required interference signal power of
interference signal SS results from the blocking condition as well
as a safely margin that is based on the fading and shadowing values
to be used and typically is in the order of 5 to 10 decibels. For
reliable maintenance of blocking conditions, because of the
variability of the mobile radio field with a lack of a measuring
device ME, assumptions must be made about the maximum power level
to be expected for the mobile radio network in the protected area
PA to be created.
The transmission blocker could be installed for example in an
aircraft that is at an airport supplied by mobile radio networks
based on the GSF standard. The interference signal SS of the
transmission blocker, which in this case lies in the GSM frequency
range, must have its strength adjusted so that the readout of the
BCCH channels of the supplying base radio stations is prevented by
the mobile telephones, or reception of messages on the TCH in
mobile telephones that are being used for telephony is suppressed.
A GSM-conforming mobile telephone in this case will not attempt to
transmit The strength of interference signal SS of the transmission
blocker can be set very much lower than that of transmission signal
S of the mobile telephone, since the transmission blocker is a
great deal closer to the mobile telephone than the mobile telephone
of the fixed base radio station of the GSM network. As a result,
the influence on the safety-relevant electronics by the
transmission is very small.
Furthermore it is also possible to equip a transmission blocker
with a simultaneous ability to radiate various interference signals
ss, so that, various mobile radio systems and/or mobile radio
stations transmitting on different frequencies can accordingly be
temporarily prevented from transmitting in an area pa to be
protected.
* * * * *